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Cited by 299Sports Performance and TrainingMuscle metabolism and nutritionCardiovascular and exercise physiology

Periodized Nutrition for Athletes

Open access
Jeukendrup, Asker E·2017·Sports Medicine
DOI 10.1007/s40279-017-0694-2PMC PMC5371625
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Abstract

It is becoming increasingly clear that adaptations, initiated by exercise, can be amplified or reduced by nutrition. Various methods have been discussed to optimize training adaptations and some of these methods have been subject to extensive study. To date, most methods have focused on skeletal muscle, but it is important to note that training effects also include adaptations in other tissues (e.g., brain, vasculature), improvements in the absorptive capacity of the intestine, increases in tolerance to dehydration, and other effects that have received less attention in the literature. The purpose of this review is to define the concept of periodized nutrition (also referred to as nutritional training) and summarize the wide variety of methods available to athletes. The reader is referred to several other recent review articles that have discussed aspects of periodized nutrition in much more detail with primarily a focus on adaptations in the muscle. The purpose of this review is not to discuss the literature in great detail but to clearly define the concept and to give a complete overview of the methods available, with an emphasis on adaptations that are not in the muscle. Whilst there is good evidence for some methods, other proposed methods are mere theories that remain to be tested. 'Periodized nutrition' refers to the strategic combined use of exercise training and nutrition, or nutrition only, with the overall aim to obtain adaptations that support exercise performance. The term nutritional training is sometimes used to describe the same methods and these terms can be used interchangeably. In this review, an overview is given of some of the most common methods of periodized nutrition including 'training low' and 'training high', and training with low- and high-carbohydrate availability, respectively. 'Training low' in particular has received considerable attention and several variations of 'train low' have been proposed. 'Training-low' studies have generally shown beneficial effects in terms of signaling and transcription, but to date, few studies have been able to show any effects on performance. In addition to 'train low' and 'train high', methods have been developed to 'train the gut', train hypohydrated (to reduce the negative effects of dehydration), and train with various supplements that may increase the training adaptations longer term. Which of these methods should be used depends on the specific goals of the individual and there is no method (or diet) that will address all needs of an individual in all situations. Therefore, appropriate practical application lies in the optimal combination of different nutritional training methods. Some of these methods have already found their way into training practices of athletes, even though evidence for their efficacy is sometimes scarce at best. Many pragmatic questions remain unanswered and another goal of this review is to identify some of the remaining questions that may have great practical relevance and should be the focus of future research.

AI snapshot

Written from the paper’s full text.

TL;DR

This review defines “periodized nutrition” (or nutritional training) as the planned, purposeful, strategic use of nutrition to enhance training adaptations and long-term performance, and surveys methods such as train low, train high, training the gut, training dehydrated, and supplements. It concludes that some methods have good evidence, but many remain theoretical or lack demonstrated performance benefits.

Key findings

  • Periodized nutrition is defined as the planned, purposeful, and strategic use of specific nutritional interventions to enhance adaptations targeted by individual exercise sessions or periodic training plans, or to obtain other effects that enhance longer-term performance; the term is interchangeable with “nutritional training.”
  • “Train low” variations (training twice a day, fasted training, low exogenous carbohydrate availability, carbohydrate restriction during recovery, sleep low, and low-carbohydrate high-fat/ketogenic diets) generally show beneficial effects on signaling and transcription, but few studies show performance effects; for example, 3 weeks of train low produced no performance differences versus control in Hulston et al. and Yeo et al., and Burke et al. reported elite race walkers on a ketogenic diet improved −1.6% after 3 weeks of intensified training versus +6.6% in the high-carbohydrate group and +5.5% in the mixed group.
  • “Train high” is supported for maintaining training quality and reducing overreaching; Simonsen et al. found 2500-m mean power increased 10.7% in rowers consuming a high-carbohydrate diet (10 g/kg/day) versus 1.6% with normal carbohydrate (5 g/kg/day) during 4 weeks of twice-daily hard training.
  • Training the gut can improve gastric emptying and absorption and likely reduce gastrointestinal problems; training dehydrated reduced the performance decrement from dehydration (dehydration reduced performance by 2.4%; after hypohydrated training, runners were 5.8% slower when euhydrated versus 1.2% slower when dehydrated), though only one study reported this. Supplements are categorized by proposed mechanism, but mitochondrial-biogenesis supplements have the least solid evidence, and high-dose antioxidants may reduce training adaptations.

Methods

  • Narrative review that defines the concept of periodized nutrition and provides a holistic overview of methods, with emphasis on adaptations outside skeletal muscle; it refers readers to other reviews for detailed literature discussion rather than discussing studies in great detail.
  • No primary data or sample; the paper synthesizes prior studies and presents tables of nutritional training methods and supplement categories.
  • Main analysis is conceptual synthesis, including proposed definitions, method classifications, and identification of remaining practical research questions.

Limitations

  • The paper states that many proposed methods are “mere theories that remain to be tested,” evidence for efficacy is sometimes scarce, few “train low” studies show performance effects, and many pragmatic questions remain unanswered; some methods rest on very few studies (e.g., only one study on training dehydrated, only two studies on “train high–sleep low”).
  • The paper states that there are no data on ketogenic diets in athletes on which to base performance claims, and that mitochondrial-biogenesis supplements lack convincing evidence for practical guidelines.
  • Evident from the text: this is a narrative review without a systematic search, formal study-quality assessment, or meta-analysis, and the author notes the list of methods may not be exhaustive.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1007/s40279-017-0694-2

Cites

101 of 101 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 122 cited sources checked · 0 supported · 0 flagged

  • Premisecitation

    There were no differences in performance after 3 weeks of training low compared with the control.

    “However, there were no differences in performance after 3 weeks of training low compared with the control [20, 31]”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [20] Yeo WK, McGee SL, Carey AL, et al. Acute signalling responses to intense endurance training commenced with low or normal muscle glycogen. Exp Physiol. 2010;95:351–8. source

      Not checked in the free run.

    • cites [31] Hulston CJ, Venables MC, Mann CH, et al. Training with low muscle glycogen enhances fat metabolism in well-trained cyclists. Med Sci Sports Exerc. 2010;42:2046–55. source

      Not checked in the free run.

  • Premisecitation

    Oxidative enzymes CS and HAD were upregulated to a greater degree (47 and 34%, respectively) when fasted compared with fed after 6 weeks of training.

    “For example, in one study it was demonstrated that oxidative enzymes such as CS and HAD were upregulated to a greater degree (47 and 34%, respectively) when fasted was compared with fed after 6 weeks of training (4 × per week, 1–1.5 h at 75% maximal oxygen uptake) [34].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [34] Van Proeyen K, Szlufcik K, Nielens H, et al. Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Appl Physiol. 2011;110:236–45. source

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  • Premisecitation

    Morton et al. observed increased succinate dehydrogenase activity when training with low muscle glycogen.

    “Morton et al. [32] also observed beneficial adaptations (increased succinate dehydrogenase activity) when training with low muscle glycogen.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [32] Morton JP, Croft L, Bartlett JD, et al. Reduced carbohydrate availability does not modulate training-induced heat shock protein adaptations but does upregulate oxidative enzyme activity in human skeletal muscle. J Appl Physiol. 2009;106:1513–21. source

      Not checked in the free run.

  • Premisecitation

    Training in the fasted state was more effective to increase muscle oxidative capacity than training in the fed state.

    “The authors concluded that training in the fasted state was more effective to increase muscle oxidative capacity than training in the fed state.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [34] Van Proeyen K, Szlufcik K, Nielens H, et al. Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Appl Physiol. 2011;110:236–45. source

      Not checked in the free run.

  • Premisecitation

    Despite performing less work, some adaptations were greater in the train-low group.

    “Despite the fact that the former performed less work, some of the adaptations were greater.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [20] Yeo WK, McGee SL, Carey AL, et al. Acute signalling responses to intense endurance training commenced with low or normal muscle glycogen. Exp Physiol. 2010;95:351–8. source

      Not checked in the free run.

    • cites [31] Hulston CJ, Venables MC, Mann CH, et al. Training with low muscle glycogen enhances fat metabolism in well-trained cyclists. Med Sci Sports Exerc. 2010;42:2046–55. source

      Not checked in the free run.

  • Classified as probably not a substantial claim. 15
  • May combine two claims. 37

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The benefits of carbohydrate ingestion during exercise are generally recognized.

    “Although the benefits of carbohydrate ingestion during exercise are generally recognized [38–41], carbohydrate supplementation during exercise may not have only positive effects.”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [38] Jeukendrup A. The new carbohydrate intake recommendations. Nestle Nutr Inst Workshop Ser. 2013;75:63–71. source

      Not checked in the free run.

    • cites [39] Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014;44:S25–33. source

      Not checked in the free run.

    • cites [40] Stellingwerff T, Cox GR. Systematic review: carbohydrate supplementation on exercise performance or capacity of varying durations. Appl Physiol Nutr Metab. 2014;39:998–1011. source

      Not checked in the free run.

    • cites [41] Cermak NM, van Loon LJ. The use of carbohydrates during exercise as an ergogenic aid. Sports Med. 2013;43:1139–55. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Training twice a day with low muscle glycogen produced marked improvements in markers of oxidative capacity (HAD and CS) and increased glycogen levels compared with training in a glycogen-loaded state.

    “This produced marked improvements in the markers of oxidative capacity [activity of the mitochondrial enzymes 3-hydroxyacyl-CoA dehydrogenase (HAD) and citrate synthase (CS)] and increased glycogen levels compared with training in a glycogen-loaded state all the time [30].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [30] Hansen AK, Fischer CP, Plomgaard P, et al. Skeletal muscle adaptation: training twice every second day vs. training once daily. J Appl Physiol. 2005;98:93–9. source

      Not checked in the free run.

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    Premisecitation

    When training fasted, muscle glycogen should be unaffected by the overnight fast, but liver glycogen will be very low.

    “When training fasted, muscle glycogen should be unaffected by the overnight fast, but liver glycogen will be very low [33].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [33] Nilsson LH, Hultman E. Liver glycogen in man; the effects of total starvation or a carbohydrate-poor diet followed by carbohydrate feeding. Scand J Clin Lab Invest. 1973;32:325–30. source

      Not checked in the free run.

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    Premisecitation

    Intramuscular fat utilization was increased with fasted training and improvements in the regulation of blood glucose levels were observed.

    “They also observed that intramuscular fat utilization was increased with fasted training and noted improvements in the regulation of blood glucose levels.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [34] Van Proeyen K, Szlufcik K, Nielens H, et al. Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Appl Physiol. 2011;110:236–45. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In that study, small changes were observed in proteins involved in the regulation of fat metabolism but this did not result in measurable changes in fat oxidation.

    “In this study, small changes were observed in proteins involved in the regulation of fat metabolism but this did not result in measurable changes in fat oxidation.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [37] De Bock K, Derave W, Eijnde BO, et al. Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake. J Appl Physiol. 2008;104:1045–55. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    HAD and FAT/CD36 protein content was increased more when training low and the ability to use fat as a fuel was improved.

    “Hulston et al. [31] reported that HAD and fatty acid translocase (FAT/CD36) protein content was increased more when ‘training low’ and the ability to use fat as a fuel was improved [20, 31].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [20] Yeo WK, McGee SL, Carey AL, et al. Acute signalling responses to intense endurance training commenced with low or normal muscle glycogen. Exp Physiol. 2010;95:351–8. source

      Not checked in the free run.

    • cites [31] Hulston CJ, Venables MC, Mann CH, et al. Training with low muscle glycogen enhances fat metabolism in well-trained cyclists. Med Sci Sports Exerc. 2010;42:2046–55. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Training twice a day may result in adaptations that favor fat metabolism, but it is too early to conclude that this training method will also result in long-term performance benefits.

    “It appears that training twice a day may result in adaptations that favor fat metabolism, but it is too early to definitely conclude that this training method will also result in long-term performance benefits.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationreasoning

    If the goal is to develop fat metabolism specifically, training with low-carbohydrate availability may achieve these specific adaptations.

    “For example, if the goal is to develop fat metabolism specifically, there may be a role of training with low-carbohydrate availability that will achieve these specific adaptations.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationnone given

    The selection of nutritional training methods is highly specific to the goals.

    “The terms periodized nutrition and nutritional training can be used interchangeably and the selection of nutritional training methods is highly specific to the goals.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Exercise in the fasted state facilitated intramuscular fat use during exercise and improved glycogen resynthesis.

    “De Bock et al. [35] showed that exercise in the fasted state facilitated intramuscular fat use during exercise and improved glycogen resynthesis [35].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [35] De Bock K, Richter EA, Russell AP, et al. Exercise in the fasted state facilitates fibre type-specific intramyocellular lipid breakdown and stimulates glycogen resynthesis in humans. J Physiol. 2005;564:649–60. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Van Proeyen et al. found no differences in AMPK in subjects training in the fasted vs. fed state, but did observe differences in post-exercise eukaryotic elongation factor 2 phosphorylation.

    “Van Proeyen et al. [36] found no differences in AMPK in subjects training in the fasted vs. fed state, but did observe differences in post-exercise eukaryotic elongation factor 2 phosphorylation (elevated after carbohydrate feeding but not after fasting).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [36] Van Proeyen K, De Bock K, Hespel P. Training in the fasted state facilitates re-activation of eEF2 activity during recovery from endurance exercise. Eur J Appl Physiol. 2011;111:1297–305. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    After 24 h, glycogen replenishment was similar in the two groups and gene expression levels returned to baseline levels in both groups.

    “After 24 h, glycogen replenishment was similar in the two groups (a finding that seems consistent in well-trained individuals) and gene expression levels returned to baseline levels in both groups.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [60] Jensen L, Gejl KD, Ortenblad N, et al. Carbohydrate restricted recovery from long term endurance exercise does not affect gene responses involved in mitochondrial biogenesis in highly trained athletes. Physiol Rep. 2015;3:e12184. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In a recent study, carbohydrate intake resulted in partial glycogen replenishment but gene expression was not different between the carbohydrate intake and carbohydrate restriction groups.

    “The carbohydrate intake resulted in partial glycogen replenishment but gene expression was not different between the two groups.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [60] Jensen L, Gejl KD, Ortenblad N, et al. Carbohydrate restricted recovery from long term endurance exercise does not affect gene responses involved in mitochondrial biogenesis in highly trained athletes. Physiol Rep. 2015;3:e12184. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    A high-fat diet will increase fat oxidation, perhaps by increasing enzyme activity related to fat metabolism, but can reduce enzyme activities related to carbohydrate metabolism.

    “A study by Stellingwerff et al. [54] demonstrated that although a high-fat diet will increase fat oxidation, perhaps by increasing enzyme activity related to fat metabolism, it can reduce enzyme activities related to carbohydrate metabolism.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [54] Stellingwerff T, Spriet LL, Watt MJ, et al. Decreased PDH activation and glycogenolysis during exercise following fat adaptation with carbohydrate restoration. Am J Physiol. 2006;290:E380–8.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Improvements in supramaximal cycling time to exhaustion were reported with sleep low but not control.

    “Interestingly, the authors also reported improvements in supramaximal cycling time to exhaustion with sleep low but not control.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [62] Marquet LA, Brisswalter J, Louis J, et al. Enhanced endurance performance by periodization of carbohydrate intake: “sleep low” strategy. Med Sci Sports Exerc. 2016;48:663–72. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Other studies could not confirm this and found no differences between a high- and a low-carbohydrate intake during recovery.

    “Other studies, however, could not confirm this and found no differences between a high- and a low-carbohydrate intake during recovery [58–60].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [58] Mathai AS, Bonen A, Benton CR, et al. Rapid exercise-induced changes in PGC-1alpha mRNA and protein in human skeletal muscle. J Appl Physiol. 2008;105:1098–105. source

      Not checked in the free run.

    • cites [59] Cluberton LJ, McGee SL, Murphy RM, et al. Effect of carbohydrate ingestion on exercise-induced alterations in metabolic gene expression. J Appl Physiol. 2005;99:1359–63. source

      Not checked in the free run.

    • cites [60] Jensen L, Gejl KD, Ortenblad N, et al. Carbohydrate restricted recovery from long term endurance exercise does not affect gene responses involved in mitochondrial biogenesis in highly trained athletes. Physiol Rep. 2015;3:e12184. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Enzymes involved in fat oxidation were upregulated and fat oxidation was increased with a low-carbohydrate, high-fat diet.

    “Enzymes involved in fat oxidation were upregulated and fat oxidation was increased [49].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [49] Burke LM, Angus DJ, Cox GR, et al. Fat adaptation with carbohydrate recovery promotes metabolic adaptation during prolonged cycling. Med Sci Sports Exerc. 1999;31:297 [abstract]. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    p38 MAPK was activated more when carbohydrate intake was restricted and this has been linked to enhanced expression of peroxisome proliferator-activated receptor-γ coactivator 1 and an improved metabolic adaptation to exercise.

    “Specifically, it was observed that p38 MAPK was activated more when carbohydrate intake was restricted and this has been linked to enhanced expression of peroxisome proliferator-activated receptor-γ coactivator 1 and an improved metabolic adaptation to exercise.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [21] Cochran AJ, Little JP, Tarnopolsky MA, et al. Carbohydrate feeding during recovery alters the skeletal muscle metabolic response to repeated sessions of high-intensity interval exercise in humans. J Appl Physiol. 2010;108:628–36. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In a follow-up study, 10-km running performance increased after 3 weeks in the sleep-low group but not in the control group.

    “The authors found a small but significant effect on performance as 10-km running performance increased after 3 weeks in the ‘sleep-low’ group but not in the control group.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [62] Marquet LA, Brisswalter J, Louis J, et al. Enhanced endurance performance by periodization of carbohydrate intake: “sleep low” strategy. Med Sci Sports Exerc. 2016;48:663–72. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Performance of high-intensity exercise was not improved by 3 weeks of intensified training in the ketogenic diet group (−1.6%), while athletes consuming the other diets made substantial performance improvements (6.6% in the high-carbohydrate group and 5.5% in the mixed group).

    “In fact, performance of high-intensity exercise was not improved by 3 weeks of intensified training in the ketogenic diet group (−1.6%), while athletes consuming the other diets made substantial performance improvements (6.6% in the high-carbohydrate group and 5.5% in the mixed group).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [55] Burke LM, Ross ML, Garvican-Lewis LA, et al. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intesified training in elite race walkers. 2016. doi: 10.1113/JP273230 (Epub ahead of print). source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Glucose ingestion suppresses lipolysis and reduces the concentration of fatty acids in the plasma, and this possibly attenuates some of the training-induced adaptations.

    “Glucose ingestion will suppress lipolysis and reduce the concentration of fatty acids in the plasma, and this possibly attenuates some of the training-induced adaptations.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Traditionally, it was recommended to consume carbohydrate immediately after exercise as this results in the highest rates of glycogen synthesis.

    “Traditionally, it was recommended to consume carbohydrate immediately after exercise as this results in the highest rates of glycogen synthesis [56].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [56] Burke LM, van Loon LJ, Hawley JA. Post-exercise muscle glycogen resynthesis in humans. J Appl Physiol (1985). 2016:jap.00860.2016. doi: 10.1152/japplphysiol.00860.2016 (Epub ahead of print). source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Subjects felt more fatigued and exercise capacity was reduced with a low-carbohydrate high-fat practice.

    “However, it was also observed that subjects felt more fatigued [47] and exercise capacity was reduced with this practice [48].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [47] Krogh A, Lindhard J. The relative value of fat and carbohydrate as sources of muscular energy. Biochem J. 1920;14:290–363. source

      Not checked in the free run.

    • cites [48] Christensen EH, Hansen O. Arbeitsfähigkeit und Ernährung. Scand Arch Physiol. 1939;81:160–71. source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    There is no method (or diet) that will address all needs of an individual in all situations.

    “Which of these methods should be used depends on the specific goals of the individual and there is no method (or diet) that will address all needs of an individual in all situations.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    A ketogenic diet containing less than 20 g of carbohydrate per day for 4 weeks resulted in hyperketonemia and increases in fat oxidation.

    “In the 1980s, a study with five subjects showed that a ketogenic diet, containing less than 20 g of carbohydrate per day, for a prolonged period of time (4 weeks) resulted in hyperketonemia and increases in fat oxidation [53].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [53] Phinney SD, Bistrian BR, Evans WJ, et al. The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism. 1983;32:769–76. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In that study, exercise capacity was only tested at a low intensity and showed a large degree of variation; on average, there was no difference in exercise capacity before and after the ketogenic diet.

    “In this study, exercise capacity was only tested at a low intensity and showed a large degree of variation both between subjects and within subjects. On average, there was no difference in exercise capacity before and after the ketogenic diet.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [53] Phinney SD, Bistrian BR, Evans WJ, et al. The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism. 1983;32:769–76. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Significant increases were observed in CS and HAD activities after the 10-week training program but there was no effect of carbohydrate supplementation on these changes.

    “Significant increases were observed in CS and HAD activities after the 10-week training program but there was no effect of carbohydrate supplementation on these changes.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [46] Akerstrom TC, Krogh-Madsen R, Petersen AM, et al. Glucose ingestion during endurance training in men attenuates expression of myokine receptor. Exp Physiol. 2009;94:1124–31. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Long-term suppression of AMPK could reduce the increase in CS activity and reduce muscle glycogen accumulation.

    “Glucose ingestion can attenuate the rise in AMPK [42], and long-term suppression of AMPK in turn could reduce the increase in CS activity [43] and reduce muscle glycogen accumulation [44], two common markers of training adaptation.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [43] Winder WW, Holmes BF, Rubink DS, et al. Activation of AMP-activated protein kinase increases mitochondrial enzymes in skeletal muscle. J Appl Physiol. 2000;88:2219–26. source

      Not checked in the free run.

    • cites [44] Holmes BF, Kurth-Kraczek EJ, Winder WW. Chronic activation of 5′-AMP-activated protein kinase increases GLUT-4, hexokinase, and glycogen in muscle. J Appl Physiol. 1999;87:1990–5. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Training the gut could potentially help develop gut adaptations that improve nutrient delivery, especially carbohydrate, and reduce the prevalence or severity of GI symptoms during exercise.

    “Training the gut could potentially help with the development of gut adaptations that improve the delivery of nutrients (especially carbohydrate), and reduce the prevalence or severity of GI symptoms during exercise.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Gastrointestinal problems are very common among endurance athletes, and the incidence of GI problems in endurance events is high.

    “Gastrointestinal problems are very common amongst endurance athletes, ranging from mild to severe.”
    • Also stated in: § Training the Gut · plain
      “The incidence of GI problems in athletes participating in endurance events is high [70]”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [70] de Oliveira EP, Burini RC, Jeukendrup A. Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations. Sports Med. 2014;44:S79–85. source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductnone given

    Most studies of caffeine have studied exercise lasting around 1 h, while for NaHCO3 and nitrates the studied exercise is typically between 1 and 10 min.

    “It must be realized that for caffeine, most studies have studied exercise lasting around 1 h and for NaHCO3 and nitrates typically between 1 and 10 min.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    Appropriate practical application lies in the optimal combination of different nutritional training methods.

    “Therefore, appropriate practical application lies in the optimal combination of different nutritional training methods.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Nutritional training can improve gastric emptying and absorption, and likely reduce the chances and/or severity of GI problems, thereby improving endurance performance and athlete experience.

    “It is clear that ‘nutritional training’ can improve gastric emptying and absorption, and likely reduce the chances and/or severity of GI problems, thereby improving endurance performance as well as ensuring a better experience for the athlete.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    A high-carbohydrate diet increases the number of sodium glucose co-transporter transporters in the intestine and their activity, allowing greater carbohydrate absorption and oxidation during exercise.

    “For example, a high-carbohydrate diet will increase the number of sodium glucose co-transporter transporters in the intestine as well as the activity of the transporters [75–78], allowing greater carbohydrate absorption and oxidation during exercise [74].”
    Quote in the paperSubstantial claim0 of 5 sources checked
    • cites [75] Ferraris RP, Villenas SA, Hirayama BA, et al. Effect of diet on glucose transporter site density along the intestinal crypt-villus axis. Am J Physiol. 1992;262:G1060–8.

      Not checked in the free run.

    • cites [76] Dyer J, Al-Rammahi M, Waterfall L, et al. Adaptive response of equine intestinal Na+/glucose co-transporter (SGLT1) to an increase in dietary soluble carbohydrate. Pflugers Arch. 2009;458:419–30. source

      Not checked in the free run.

    • cites [77] Ginsburg JM, Heggeness FW. Adaptation in monosaccharide absorption in infant and adult rats. J Nutr. 1968;96:494–8. source

      Not checked in the free run.

    • cites [78] Karasov WH, Pond RS 3rd, Solberg DH, et al. Regulation of proline and glucose transport in mouse intestine by dietary substrate levels. Proc Natl Acad Sci USA. 1983;80:7674–7. source

      Not checked in the free run.

    • cites [74] Cox GR, Clark SA, Cox AJ, et al. Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. J Appl Physiol. 2010;109:126–34. source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductcitation

    These studies used an extreme training volume to simulate a training camp situation, and after 1-2 weeks performance decreased in all groups.

    “However, it must be noted that these studies used an extreme training volume to simulate a training camp situation and the result after 1–2 weeks was a decreased performance in all groups.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [64] Achten J, Halson SL, Moseley L, et al. Higher dietary carbohydrate content during intensified running training results in better maintenance of performance and mood state. J Appl Physiol. 2004;96:1331–40. source

      Not checked in the free run.

    • cites [66] Halson SL, Lancaster GI, Achten J, et al. Effects of carbohydrate supplementation on performance and carbohydrate oxidation after intensified cycling training. J Appl Physiol. 2004;97:1245–53. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    On average, runners were 5.8% slower with euhydrated training and only 1.2% slower when they trained in a dehydrated state.

    “On average, the runners were 5.8% slower with euhydrated training and only 1.2% slower when they trained in a dehydrated state.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [79] Fleming J, James LJ. Repeated familiarisation with hypohydration attenuates the performance decrement caused by hypohydration during treadmill running. Appl Physiol Nutr Metab. 2014;39:124–9. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Gastric emptying and stomach comfort can be trained, and perceptions of fullness can be decreased.

    “Gastric emptying as well as stomach comfort can be ‘trained’, perceptions of fullness decreased [71]”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [71] Lambert GP, Lang J, Bull A, et al. Fluid tolerance while running: effect of repeated trials. Int J Sports Med. 2008;29:878–82. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationnone given

    The effects on longer term performance or the effects of more moderate training with higher or lower carbohydrate are understudied.

    “Although the train-high group seemed to recover better, the effects on longer term performance or the effects of more moderate training with higher or lower carbohydrate are understudied.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Such supplements could potentially improve long-term training adaptations because they would allow a greater training load or higher quality of training.

    “Such supplements could potentially improve long-term training adaptations because they would allow a greater training load or higher quality of training.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Green tea extracts increase fat oxidation and performance in mice, but in humans these effects were not found after 7-28 days of green tea extract supplementation.

    “For example, while green tea extracts (containing the active component epicatechin and epigallocatechin gallate) have been shown to increase fat oxidation and performance in mice [94], in humans, these effects were not found [95] after 7–28 days of green tea extract supplementation.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [94] Murase T, Haramizu S, Shimotoyodome A, et al. Green tea extract improves running endurance in mice by stimulating lipid utilization during exercise. Am J Physiol. 2006;290:R1550–6.

      Not checked in the free run.

    • cites [95] Randell RK, Hodgson AB, Lotito SB, et al. Variable duration of decaffeinated green tea extract ingestion on exercise metabolism. Med Sci Sports Exerc. 2014;46:1185–93. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

    Interpretationnone given

    Which methods should be used depends on the specific goals of the individual, and no methods will address all needs.

    “Which of these methods should be used depends on the specific goals of the individual and there are no methods that will address all needs.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Training adaptations are the result of a complex interplay between nutrition and exercise.

    “In summary, training adaptations are the result of a complex interplay between nutrition and exercise.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    Methods to improve gut function, including faster absorption and reduced GI distress, have been developed.

    “In addition, because the gut is an important organ, methods to improve gut function (faster absorption and reduced GI distress) have also been developed.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    Several strategies have been developed to promote training adaptations, some of which have more evidence in support than others.

    “Several strategies have been developed to this effect, some of which have more evidence in support than others.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    Not all studies have demonstrated such effects, and differences between studies may be a function of the specific antioxidants used, and the dose and timing of intake.

    “Not all studies have demonstrated such effects and differences between studies may be a function of the specific antioxidants used, and the dose and timing of intake [96].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [96] Mankowski RT, Anton SD, Buford TW, et al. Dietary antioxidants as modifiers of physiologic adaptations to exercise. Med Sci Sports Exerc. 2015;47:1857–68. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    The most common methods are training with high-carbohydrate availability (train high) and training with low-carbohydrate availability (train low).

    “The most common methods are training with high-carbohydrate availability (train high) and training with low-carbohydrate availability (train low).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Carbohydrate intake can be used to improve the total amount of work done in training.

    “As discussed in Sect. 4.2, carbohydrate intake can also be used to improve the total amount of work done in training.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    Certain ingredients (supplements) may increase the effects of training.

    “There are also certain ingredients (supplements) that may increase the effects of training.”
    Quote in the paperNot a substantial claim
48 of 48

  • The paper relies on this without support.

    The adaptive response to exercise training is determined by a combination of duration, intensity, type, frequency, and the quality and quantity of nutrition in the pre- and post-exercise periods.

    “The adaptive response to exercise training is determined by a combination of factors: the duration, the intensity, and the type of exercise as well as the frequency of training, but also by the quality and quantity of nutrition in the pre- and post-exercise periods.”

  • The paper relies on this without support.

    In the absence of protein feeding post-exercise, net protein synthesis is low and the muscle may be in negative protein balance.

    “For example, it is well established that in the absence of protein feeding post-exercise, net protein synthesis is low and the muscle may actually be in negative protein balance.”

  • The paper relies on this without support.

    Research has mostly focused on adaptations in skeletal muscle.

    “Research has mostly focused on adaptations in skeletal muscle.”

  • The paper relies on this without support.

    A clear definition and a common interpretation of periodized nutrition is lacking.

    “In the literature, the term ‘periodized nutrition’ is sometimes used, but a clear definition and a common interpretation is lacking.”

  • The paper relies on this without support.

    Most nutritional recommendations for athletes aim to promote acute recovery after exercise without acknowledging the specific goal of the exercise and often without taking into account the severity and type of exercise or the longer term goals.

    “Most nutritional recommendations for athletes aim to promote acute recovery after exercise without acknowledging the specific goal of the exercise and often without taking into account the severity and type of exercise or the longer term goals.”

  • The paper relies on this without support.

    Only two studies exist on the concept of ‘train high-sleep low’.

    “These are the only two studies on the concept of ‘train high-sleep low’”
6 of 6

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Authors
Jeukendrup, A. E.
Affiliations
Loughborough University (GB)
Corresponding author
Jeukendrup, Asker E
Venue
Sports Medicine
Publisher
Springer Science and Business Media LLC
Published
2017-03
Volume
47
Issue
S1
Pages
51-63
ISSN
  • 0112-1642 (ISSN-L)
  • 1179-2035
DOI
10.1007/s40279-017-0694-2
PMC
PMC5371625
OpenAlex
W2600177218
Semantic Scholar
8d0e3d678a09aee6b9f0bb812e486fd35d0b0a53
Cited by
299
References
101
Citations by year
2026: 28 · 2025: 44 · 2024: 41 · 2023: 31 · 2022: 24 · 2021: 47 · 2020: 29 · 2019: 31 · 2018: 19 · 2017: 5
FWCI
4.17
Type
journal article
Language
en
Open access
Licence
Locations
  • Sports Medicine (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • PepsiCo
  • Gran Sasso Science Institute
Topics
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
Keywords
athletes, training effects, carbohydrate availability, hypohydration, dehydration tolerance, dietary supplements, exercise performance, skeletal muscle adaptation
MeSH terms
Diet, Humans, Nutritional Status, Physical Education and Training, Exercise, Muscle, Skeletal, Athletic Performance, Athletes

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Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-07.

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